This is different from a quick chat export
If you only need a searchable plain-text copy of a conversation for your own reference, a basic chat-export feature (like exporting a WhatsApp chat as text) is faster. Printing to a document is worth the extra steps specifically when you need a nicely formatted, shareable, or physically handed-over record -- for example as evidence in a dispute or a formal complaint.
Desktop apps, not mobile, usually have full export options
Most messaging apps only offer detailed, formatted chat export (like HTML with layout preserved) on their desktop app rather than mobile, so you may need to install the desktop version on a computer first even if you normally only use the app on your phone.
Frequently Asked Questions
Can I print a chat directly from my phone without a computer?
It is possible by taking screenshots and printing those, but for a clean, complete document with the full conversation, exporting on a desktop app and printing from a browser or word processor gives a much more readable result.
Does the exported file include photos and attachments?
Most export tools let you choose whether to include media files alongside the text -- including media produces a larger file and folder structure, so choose text-only if you just need the printed conversation.